While high-profile urban tree planting campaigns like New York City’s get a lot of attention, most U.S. cities have experienced a decline in their urban forests, with a loss of about 4 million trees each year, or about “1.3 percent of the total tree stock.” The Nature Conservancy builds the case for recommitting to expanding our urban canopies for health reasons, instead of just letting them slowly diminish.

The many benefits of trees are well-documented: they clean and cool the air, combat the urban heat island effect, capture stormwater, mitigate the risk of floods, boost water quality, and, importantly, improve our mental…